Dead rare dolphin and whale found

The Risso's dolphin may have been attacked by bottlenose dolphins

The bodies of two "highly unusual" marine mammals have washed ashore in the Isles of Scilly.

Cornwall Wildlife Trust said both were found on the western shores of St Agnes within days of one another.

The first was a very rare 12ft (3.6m) Sowerby's beaked whale - normally a deep water species which feeds off squid and cuttlefish.

Days later a Risso's dolphin calf was discovered less than quarter of a mile away (about 402m).

The trust said, despite the sad death of both mammals, it provided a unique opportunity for local scientists to examine them.

The Sowerby's whale was too big to be taken for a post-mortem examination, but members of the trust's Marine Strandings' Network collected measurements, photographs and skin samples to be analysed by the Institute of Zoology.

St Agnes Coastguard Mike Hicks, who found the animal, said: "It was sad to see such an impressive animal out of her natural environment but I'm pleased we were able to help gather information from her.

"It was a privilege to see something that most people never will."

When Mr Hicks was alerted to the dolphin, he sent photographs to the Marine Strandings Network who identified it as a Risso.

Risso's dolphins are often seen around Cornwall, although not as frequently as bottlenose and common dolphins.

The Sowerby's beaked whale was found by the local coastguard

The dead animal was taken to the mainland for post mortem tests at the Veterinary Laboratories Agency in Truro.

The trust said initial observations suggested it had been killed by bottlenose dolphins.

This phenomenon has previously been recorded in the Moray Firth, Scotland, with bottlenose dolphins attacking and killing harbour porpoises.

The motives are unclear, although scientists have considered that competition for declining food stocks may trigger the behaviour.

"Despite their friendly image, bottlenose dolphins can be aggressive towards one another and on the rare occasion that we see a dead bottlenose wash ashore, it often has rake, or tooth marks inflicted by its own species," Marine Strandings' Network co-ordinator Jan Loveridge said.

"However, we have recently begun to see an increase in the numbers of young and female harbour porpoise that have clearly been attacked by bottlenose dolphins and results from the post mortems carried out on these animals confirm this."